For enhanced vehicle safety, various studies have been conventionally conducted to improve the braking performance and driving performance of a tire on a variety of road surfaces including not only a dry road surface but also a wet road surface and an ice/snow road surface.
For example, the following tire has been disclosed to improve the tire performance on the ice/snow road surface. A rubber composition containing fiber that includes a resin is used in the tread, and long bubbles coated with the resin are formed after vulcanization. The long bubbles function as drainage channels as the tread wears, thus improving the drainage performance (for example, see Patent Literatures (PTLs) 1 and 2). Attempts have also been made to use a hydrophilic resin as the resin, to provide better drainage through its affinity for water.
However, improved on-ice performance with a reduced rolling resistance has not been achieved yet.
Typically, lowering the degree of foaming to improve the on-ice performance enhances the grip but also increases the rolling resistance.
There has thus been a strong need to improve the on-ice performance of the tire while reducing the rolling resistance of the tire.